The present invention relates to a scaffold plank for providing a supporting floor or walkway platform for workers.
The scaffold planks are commonly used, for example, in construction and repair industries. The scaffolod planks are, when in use, mounted on a scaffolding frame erected at a work site to form the walkway platform as disclosed, for example, in U.S. Pat. No. 3,726,362 to Puckett and U.S. Pat. No. 3,565,212 to Johnson.
Typical conventional scaffold planks are made of wood as disclosed, for example, in the above referred U.S. Pat. No. 3,726,362. However, the wooden scaffold plank is generally not so reliable from the viewpoint of safety and durability. When the wooden plank gets wet, it becomes slippery (dangerous) and heavy (inconvenient in transportation). In addition, it becomes easily weakened when repeatedly exposed to rains.
Another typical conventional scaffold planks are made of metal as disclosed, for example, in Japanese Utility Model Publication No. 3074/67 (Application No. 10193/64, filed Feb. 14, 1964) and U.S. Pat. No. 3,556,254 to Lambert. The former has proposed a steel-made scaffold plank coated with synthetic resin layer, which is heavy due to its nature and inconvenient in practical use. The latter has proposed a telescopical scaffold plank made of lightweight durable sheet metal such as aluminium. The telescopical structure may be convenient in transportation and storage, but expensive to manufacture and dangerous when the plank in use is unexpectedly retracted. Further, a worker may trip against a stepped portion inevitably formed at every joint portion of adjacent telescopical members forming a walkway surface. Furthermore, at a work site for construction or the like, clumps of fresh concrete frequently stick to and become hardened on the metal surface of the plank, resulting in corrosion by alkali content thereof. Still further, it is not very easy to remove clumps of hardened concrete stuck on the metal surface of the plank, because the fresh concrete can adhere much better to the metal surface as compared to the wooden surface of the synthetic resinous surface.
Other conventional scaffold planks are basically made of synthetic resin and reinforced with rigid materials. One model of such planks is disclosed in Japanese Utility Model Publication No. 1251/72 (Application No. 29634/68, filed Apr. 12, 1968), in which a scaffold plank has a rigid skeleton entirely wrapped with a FRP layer, the skeleton being composed of a lightweight core, formed of foamed plastics or made of reinforced paper tube, and a FRP layer enclosing the core. However, this type of plank has proved to be rather expensive to manufacture, and not very sufficient in flexural strength unless the plank is considerably thick.
Other models of the plastic plank have been proposed by the Applicant himself of the present invention, as disclosed in Japanese Patent Publication Nos. 1217/77 (Application No. 98537/70, filed Nov. 9, 1970) and 21154/80 (Application No. 98538/70, filed Nov. 9, 1970), wherein a plurality of reinforcements such as pipes are embedded in a plastic plank body. However, these prior inventions of the Applicant have such disadvantages that the end portions of the plank are easily damaged or deformed when the plank falls down against the ground or collides against something, and that muddy water, rain water or other are permitted to come into the pipes through the opening mouths thereof, adding weight and inviting corrosion.
Accordingly, it is a general object of the present invention to eliminate the above discussed disadvantages inherent to the prior art scaffold planks.
Another object of the invention is to provide an improved scaffoled plank which is light in weight, inexpensive and easy to manufacture, sufficient in flexural strength and rigidity, and good in appearance.
A further object of the invention is to provide an improved scaffold plank which is protected from corrosion, deformation and damage at the ends of the plank, and incoming of mud, water and other foreign matters.
A still further object of the invention is to provide an improved scaffold plank which permits easy removal of clumps of hardened concrete sticking to the outer surface thereof.
In order to fulfill the above objects and advantageous features, the scaffold plank according to the present invention includes a plurality of lightweight square hollow elongated members transversely aligned in side-by-side contact or otherwise a single piece of partitioned square tubular member, which provides lightweight and sufficient flexural strength and rigidity, and permits manufacture at a relatively low cost.
The plank of the invention further includes a covering member or members, preferably formed of synthetic resinous material, which provides good and colorful appearance and permits easy removal of clumps of hardened concrete sticking to the outer surface of the plank.
The plank of the invention further includes a pair of end members mounted to the opposite ends of the plank, by which deformation and/or damage at the plank ends can be prevented and also mud, water and other undesirable foreign matters are hindered from coming into the hollow elongated members. Each of the end members has a plurality of plug portions which are transversely aligned in spaced-apart relation and inwardly project into mating engagement with a corresponding number of opening mouths of the transversely aligned hollow elongated members, whereby the aligned hollow elongated members are tightly assembled to promote flexural strength and rigidity. The end member can be easily replaced, when damaged. Thus, the plank can enjoy a long span of life.
By optional provision of a pair of specifically constructed reinforcing members to be interposed between the end member and the aligned hollow elongated members, the strength and rigidity, and hence durability, can be more enhanced.
Further, the covering member and the end members, both made of non-corrosive materials, cooperate to protect the plank from corrosion. The whole structure of the plank according to the present invention is relatively simple and mass-producible.
Other objects, features and advantages of the present invention will become apparent from the detailed description given hereinafter; it shoud be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become obvious to those skilled in the art from this detailed description.